Water mass dynamics and biogeochemistry of the cold-water coral reef, Stjernsund, northern Norway

• Main Author: Ashastina, Kseniia
• Format: Thesis
• Language: English
• Published: 2013
• Subjects: Lophelia pertusa; North Atlantic; Northern Norway
• Online Access: https://oceanrep.geomar.de/id/eprint/27767/; https://oceanrep.geomar.de/id/eprint/27767/1/2013_Ashastina-Kseniia_MSc_Thesis.pdf

Cold-water corals are an object of world-wide research. Active exploration of the reef-building coral species has begun in the XX century with the development of the digital sea bottom mapping techniques and determines that cold-water corals can thrive in a wide range of depth below the photic zone from 43 m down to 3 380 m, but crucial ecological parameters governing the distribution are still not fully understood. In the focus of this study lies the northernmost living cold-water coral reef, known so far, which is located in the Stjernsund (70: 15′ N 22: 20′ E), Northern Norway. The main coral reef is formed by the scleractinia Lophelia pertusa. An underwater 4D Modular Laboratory, compiled of 5 landers and 2 moorings, was especially designed at the GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, to investigate the living coral communities of the Stjernsund. The elongated structure of the sound extends from SE to NW, connecting the North Atlantic with the Altafjord, is 30 km long and 3.5 km wide with the sill structure across it. From 1.06.2012 to 15.09.2012 the underwater laboratory was installed (434 and 438 POSEIDON cruises) on the sill recording oceanographically and biogeochemical data. Underwater observatory modules were installed on both slopes of the sill (one mooring and one lander on each slope) and on top of the sill (3 landers), so that the entire sill area was covered with measurements and water column, depending on the module settings, provides ADCP records. The Modular laboratory recorded the following physical and biochemical parameters: velocities and directions of the water flows, temperature, salinity, pH, turbidity, fluorescence, oxygen concentration and saturation. In this work data sets from 7 modules are analyzed in order to determine the ecological factors governing the uneven distribution of the living corals on the slopes of the sill and in order to reconstruct the water mass dynamics in the sound. The raw data was processed with the software Matlab. Results showed that ...